In diesel hydroprocessing, it is sometimes beneficial to include a dewaxing stage as part of reaction train in order to improve properties of the resulting diesel fuel such as pour point or cloud point. Such improvements in cold flow properties can, for example, allow a diesel fuel to meet a desired specification for a diesel fuel pool, or the improvements can allow a diesel fuel to be suitable for a higher value use, such as use as a winter diesel fuel. While such improvements can be desirable, performing an additional dewaxing process on a diesel fuel product typically means that additional refinery resources are consumed in order to perform the process.
U.S. Pat. No. 8,377,286 describes hydroprocessing methods for diesel fuel production. The methods include options for processing diesel fuel under sour conditions, such as in the presence of 100 wppm or more of sulfur. The dewaxing catalysts used for dewaxing of the diesel fuel include catalysts with a relatively low surface area, such as catalysts with a ratio of zeolite surface area to external surface area of at least about 80:100. The dewaxing catalysts are described as having a hydrogenation metals content of at least 0.1 wt %.
U.S. Pat. No. 8,303,804 describes hydroprocessing methods for production of jet fuels. The methods can include exposing a kerosene boiling range feedstock to a 10-member ring zeolite catalyst that also includes 0.1 wt % of a metal hydrogenation component.
U.S. Pat. No. 8,263,519 describes dewaxing catalysts that do not include a metal hydrogenation component or that include less than 0.05 wt % of a metal hydrogenation component. The dewaxing catalysts have include catalysts with a relatively low surface area, such as catalysts with a ratio of zeolite surface area to external surface area of at least about 80:100.